Stimulation of Carbonic Anhydrase Activity and Phosphorylation in Primary Astroglial Cultures by Norepinephrine

The carbonic anhydrase activity of 3‐week‐old primary astroglial cultures started from the dissociated cerebral hemispheres of neonatal rats was increased up to twofold after treatment of the cultures with 0.1 mM‐norepinephrine or histamine. Stimulation due to addition of norepinephrine was inhibited by propranolol. The carbonic anhydrase activity of primary cultures derived from the cerebellum plus brain stem regions was about fourfold greater than the activity of primary cultures started from cerebral hemispheres, but in contrast was not stimulated by norepinephrine. Treatment of the cerebral cultures with norepinephrine in the presence of 32 P resulted in a two‐ to threefold increased incorporation of 32 P into carbonic anhydrase purified from the same cultures, and this increased incorporation was inhibited by propranolol. It is suggested that one of the consequences of the stimulation of 3′,5′‐cyclic AMP levels in brain by norepinephrine is activation of astroglial carbonic anhydrase activity due to 3′5′‐cyclic AMP‐stimulated phosphorylation of the enzyme.